The present invention relates to a method of and an arrangement for longwall mining.
More particularly, the present invention concerns a method of and an arrangement for excavating material from a longwall mine.
It is known in the art of longwall mining to excavate the removed material by means of various mechanical transporters which may have different constructions, forms and configurations. The transporter may be formed as an endless belt or band conveyor, a rail-guided lifting cart conveyor, cage- or skip-winding arrangement, etc. These transporters have been used with a relative success in the conventional mechanical as well as in the hydromechanical longwall mining. However, it has been recognized that such transporters are not satisfactory with respect to the requirements made to simplicity, economy and ergonomics (i.e. biotechnological factors) of the arrangements for excavating material from the longwall mine.
As far as the economical reasons are concerned, the conventional mechanical transporters require on the one hand considerably high initial capital expenses for adequate driving means and on the other hand continuous service and attention from operators through the service life of the transporters. Besides, the transporters require considerable amount of space in a rather narrow longwall mine. Further, the transporters are very sensitive to any curves along the elongation of the mine. It is known to be a troublesome task to accommodate the mechanical transporter in a slightly curved and ascending longwall mine. Furthermore, even after the transporter has been installed, the latter is still susceptible to troubles during the mining process.
With respect to the ergonomics, the conventional transporters tend to develop dust formations during excavating the material from the longwall mine. The dust formations are most likely to develop on transition zones of the conventional transporter. The dust formation, besides its own negative affect on the operators, lead to the danger of fire or accidents and eventually to an undesirable heat emission of the material to be excavated into the atmosphere.
These disadvantages, especially important in the case where the concentration of the material to be excavated from the longwall mine is increased, are particularly negative in the hydromechanical mining with hydraulically removing the material from the longwall mine. Apart from the fact that the hydraulic fluid which should be as uniform as possible has to be directed onto the mining face (i.e. which must have no series of depressions) at an angle below 15.degree. relative to the horizon, the mining face should have a matrix rock which is not sensitive to water (if the hydraulic fluid is water) and the mine galleries should have a special cross-section. Only if all these conditions are met, the hydraulic fluid simply washes the particles off the mining face, for example, into open troughs. However, in order to overcome a considerable difference in an elevation during excavating the material from the longwall mine it is known to use pipes of pumping the fluid together with the removed particles from the mine. However, the method of excavating the removed material using open troughs has a significant disadvantage that the maxtrix rock eventually swells (i.e. soaks), which fact considerably increases the maintenance costs of such a longwall mine. Besides, the evaporation of water (which takes place due to the heat development during the mining process) increases the humidity of the air within the mine which makes the working conditions for the miners in this mine practically unbearable. Further, the fluid (i.e. water) may soak into the structure which is located below the mining face which fact leads to development of the still-water formations which negatively affect the mining process.
It is to be understood, that the above-discussed and other aerotechnical problems developed in the mine during the mining process can be solved only by way of expensive additional expenditures.
It is also known to excavate the removed material from the longwall mining hydraulically through closed tubes. Thus, for example, in the case of the hydromechanical mining there may be used a hydraulic hoist (i.e. so-called geiger-method) for excavating the removed material from the mine. However, as a rule, the hydraulic hoist requires that the excavated material to be comminuted prior to excavation so as to obtain particles of size below 30 mm, and preferably below 10 mm, which requirement makes the process of mining considerably more expensive.